The invention relates to printing devices and in particular to a new and useful apparatus and method of reducing the impact speed of printed products at the base of a fly delivery wheel in rotary printing presses.
As is known, the printed products or copies sequentially delivered by the folder of a rotary printing press must be slowed down to a speed corresponding to the sheet-by-sheet stream to be formed, which is basically obtained by means of a fly delivery wheel rotating in timed sequence with the folder.
The printed copies leaving the folder at the speed of the press butt against the base of the slower running delivery wheel are thereby braked to the circumferential speed of the base of the flies. Experience has shown that the impact speed must not exceed a certain value if damages to the printed products are to be avoided. With the outputs wanted today, however. this value is by far exceeded. Consequently, devices have been provided to reliably ensure a speed reduction to the desired value.
All prior art devices of this kind provide a braking of the printed products before they enter the delivery wheel. Now, since the difference between the speed of the press and the permissible impact speed is too large, the time needed by the braked printed products to present their leading edges at the fly base is relatively long. This no longer ensures, for example, that the devices provided for positively withdrawing products from the delivery wheel will take them off in an exact position.